By using seismic records of the 2004 magnitude 6.0 Parkfield earthquake,
we identified a burst of high-frequency seismic radiation that occurred
about 13 kilometers northwest of the hypocenter and 5 seconds after
rupture initiation. We imaged this event in three dimensions by using
a waveform back-projection method, as well as by timing distinct
arrivals visible on many of the seismograms. The high-frequency event
is located near the south edge of a large slip patch seen in most
seismic and geodetic inversions, indicating that slip may have grown
abruptly at this point. The time history obtained from full-waveform
back projection suggests a rupture velocity of 2.5 kilometers per
second. Energy estimates for the subevent, together with long-period
slip inversions, indicate a lower average stress drop for the northern
part of the Parkfield earthquake compared with that for the region
near its hypocenter, which is in agreement with stress-drop estimates
obtained from small-magnitude aftershocks. 10.1126/science.1146537
%0 Journal Article
%1 allmann_shearer:2007
%A Allmann, Bettina P.
%A Shearer, Peter M.
%D 2007
%J Science
%K geophysics seismology
%N 5854
%P 1279--1283
%R 10.1126/science.1146537
%T A high-frequency secondary event during the 2004 Parkfield earthquake
%U http://dx.doi.org/10.1126/science.1146537
%V 318
%X By using seismic records of the 2004 magnitude 6.0 Parkfield earthquake,
we identified a burst of high-frequency seismic radiation that occurred
about 13 kilometers northwest of the hypocenter and 5 seconds after
rupture initiation. We imaged this event in three dimensions by using
a waveform back-projection method, as well as by timing distinct
arrivals visible on many of the seismograms. The high-frequency event
is located near the south edge of a large slip patch seen in most
seismic and geodetic inversions, indicating that slip may have grown
abruptly at this point. The time history obtained from full-waveform
back projection suggests a rupture velocity of 2.5 kilometers per
second. Energy estimates for the subevent, together with long-period
slip inversions, indicate a lower average stress drop for the northern
part of the Parkfield earthquake compared with that for the region
near its hypocenter, which is in agreement with stress-drop estimates
obtained from small-magnitude aftershocks. 10.1126/science.1146537
@article{allmann_shearer:2007,
abstract = {By using seismic records of the 2004 magnitude 6.0 Parkfield earthquake,
we identified a burst of high-frequency seismic radiation that occurred
about 13 kilometers northwest of the hypocenter and 5 seconds after
rupture initiation. We imaged this event in three dimensions by using
a waveform back-projection method, as well as by timing distinct
arrivals visible on many of the seismograms. The high-frequency event
is located near the south edge of a large slip patch seen in most
seismic and geodetic inversions, indicating that slip may have grown
abruptly at this point. The time history obtained from full-waveform
back projection suggests a rupture velocity of 2.5 kilometers per
second. Energy estimates for the subevent, together with long-period
slip inversions, indicate a lower average stress drop for the northern
part of the Parkfield earthquake compared with that for the region
near its hypocenter, which is in agreement with stress-drop estimates
obtained from small-magnitude aftershocks. 10.1126/science.1146537},
added-at = {2012-09-01T13:08:21.000+0200},
author = {Allmann, Bettina P. and Shearer, Peter M.},
biburl = {https://www.bibsonomy.org/bibtex/2de61304733d73f911656d1ea29a58f30/nilsma},
day = 23,
doi = {10.1126/science.1146537},
interhash = {8e189171bc09a8c4a5d432b192246040},
intrahash = {de61304733d73f911656d1ea29a58f30},
issn = {0036-8075},
journal = {Science},
keywords = {geophysics seismology},
month = nov,
number = 5854,
pages = {1279--1283},
pmid = {18033878},
timestamp = {2021-02-09T13:25:06.000+0100},
title = {A high-frequency secondary event during the 2004 Parkfield earthquake},
url = {http://dx.doi.org/10.1126/science.1146537},
volume = 318,
year = 2007
}